The exhaust plume of a rocket motor is comprised of gaseous and particulate matter produced by the burning propellant, ablation products from the rocket nozzle and motor insulation, and from other sources of the rocket motor. Any interaction between the gaseous and particulate matter of the exhaust plume with the on-board sensors would result in effects to the sensors which would detrimentally affect the accomplishment of the rocket mission. The adverse effects would result from gaseous ablation, erosion by particulate matter in the plume, depositions on the sensors, or other similar interactions. The rocket motor may either be aboard the same vehicle as the sensor, or it may be aboard some other vehicle operating in the same general vicinity.
The use of an inert gas, such as, nitrogen, helium, argon, etc. has been considered for the envelopment of the exhaust gases to provide a protective layer for on-board sensors.
The use of an inert gaseous sweep of helium or argon, either heated or cold would be impractical because of their relative low supply and the difficulties of containing them during long periods of storage.
Another problem deserves consideration when considering a gaseous species for use as the enveloping media. The problem concerns whether or not the gaseous species is optically-inactive. For example, in order to compensate for any attenuation or degradation of the detector's performance, the species which occur in the exhaust plume must be optically inactive in the detector's infrared spectral bandpass region or must be enveloped by some optically-inactive gas which interposes itself between the exhaust plume and the sensor. The optically-inactive gas would also have to be capable of wiping the deposition off the optical mirrors of the sensor. The deposition could result from the condensation or the freezing of condensible vapors, such as, water. Additionally, the plating out of particulate matter on the optical mirrors of the sensor could be another effect which an interposing, optically-inactive gas would prevent from taking place or if it did occur, the gas would then wipe off any deposition from the optical mirrors of the sensor.
Earlier considerations which relate to two types of inert gas generators did not yield favorable results to solve present problem since the two types of gas generators, sodium azide generators and heated, stored, inert gas generators, require cumbersome accessory equipment to be described. The size and weight of this accessory equipment would render these type generators impractical for the intended use. The principles of operation of these conventional gas generators are as follows: The sodium azide gas generator requires the use of a Viton-fluorocarbon binder to impart proper mechanical properties to the gas generator grain so that it will withstand the forces that it will be subjected to in use. When the sodium azide undergoes decomposition, the use of a De-Mister and a cyclone separator is required to remove the liquid sodium and the solid constituents, such as, sodium fluoride from the efflux which is produced.
The same need exists in the alternate conventional gas generator. Here the removal of the solid exhaust products of NaF and NaCl from the exhaust products of the gas generator based on the reaction of chlorine trifluoride and sodium azide to produce nitrogen gas is used. This is illustrated in the following equation: EQU ClF.sub.3 +NaN.sub.3 .fwdarw.6N.sub.2 +3NaF+NaCl
A necessary desirable and particularly significant concern of this disclosure demands the use of gas generants which do not exhaust inorganic solids.
Therefore, an object of this invention is to provide gas generants which do not produce inorganic solids.
Another object of this invention is to provide gas generants which have the desirable physical and chemical properties which enables them to be used without the need for accessory equipment to purify the effluent products produced by the gas generants.
A further object of this invention relates to the method of using the pertinent gas generants on board advanced ballistic missile interceptors to prevent the adverse interaction between rocket exhaust plume and the on-board sensors of the interceptors.